Process for producing polyesters of improved rubber adhesion and product

ABSTRACT

Rubber adhesion properties of fibrous polyester materials are improved by a process which comprises applying a solution of an amine compound, such as polyethylene imine, to said fibrous material, subjecting the resulting fibrous material to heat treatment and then treating said fibrous material with an organic solvent solution of a polycarboxylic acid halide such as adipic acid dichloride.

United States Patent 9 H 1 Shirano et al.

PROCESS FOR PRODUCING POLYESTERS OF IMPROVED RUBBER ADHESIONAND PRODUCTInventors: Kenji Shirano; Toshihiko Yoshitake, both of Kurashiki, JapanAssignee: Kuraray Co., Kura shilti, .l apan Filed: April 15, 1971 Appl.No.: 134,418 I US. Cl. ..117/76 T, 117/7, 117/47 A, 117/63,117/72,117/77,117/80,1l7/l38.8

Int. CL, ..B32b 25/08, B32b 27/36 Field of Search 17/47 A, 138.8 F, 76T, 77, 117/72, 80, 161 P; 156/331, 110A 1 Feb. 13, 1973 [56] ReferencesCited UNITED STATES PATENTS 3,449,200 6/1969 Kalafus et a1. ..1 17/47 AX 3,305,430 2/1967 l-lennemann ..156/331 X 3,607,507 9/1971 Enos..156/331 X 3,597,391 8/1971 Hara etal ...117/l61 PX 3,499,853 3/1970Griebsch et a1 ..l56/331 X Primary ExaminerRalph l-lusackAttorneyWi11iam Kaufman and Barry Kramer ABSTRACT 20 Claims, No DrawingsPROCESS FOR PRODUCING POLYESTERS OF IMPROVED RUBBER ADHESION AND PRODUCTThis invention relates to improved polyesters. More particularly, thisinvention relates to polyesters of improved rubber adhesion and tomethods of improving adhesion of fibrous polyester materials to rubberby modifying said fibrous materials.

Fibrous polyester materials such as, for example, filaments, yarns,strands, cords, cord-fabrics and the like, generally exhibit desirableproperties as reinforcing materials for rubber, such as excellenttensile strength, shock resistance, stretch resistance, dimensionalstability, heat resistance, chemical resistance and imperviousness towater.

The adhesive force, however, necessary for their practical applicationhas been difficult to obtain by conventional adhesion treatments. Forinstance, the use of aqueous dispersions of a mixtureof apartiallycondensed resorcinol-formaldehyde resin and a vinylpyridine copolymerlatex, so-called RFL dispersion bonding agent, which is recognized asquite useful in bonding nylons and cellulose fibers to rubber, does notresult in strong adhesion of polyester materials to rubber.

in view of the above, various preliminary treatments of the polyesterhave been proposed in combination with the known RFL bonding agents. Forexample, it is known that yarns, cords and fabrics of polyester can betreated with an aqueous solution of polyethylene imine (British Pat. No.962,174') and the polyester filament can be treated with an aqueousdispersion of an expensive epoxy compound such as glycerol diglycidylether and an amine (US. Pat. No. 3,297,467). However, these methods donot impart sufficient rubber adhesion properties to polyesters. Becauseof the lack of sufficient adhesive forces at high temperatures, it hasheretofore been difficult to use polyester materials treated by theaforesaid methods for the manufacture of rubber articles such asautomotive tires and belts which are subjected to continuous bending orflexing for long periods of time.

Accordingly, it is an object of the present invention to providepolyesters exhibiting enhanced rubber adhesion.

It is another object of the present invention to provide an improvedvmethod of pretreating fibrous polyester materials in order to impartstrong rubber adhesion properties thereto.

Still another object of the present invention is to provide pretreatedfibrous polyester materials which can be bonded strongly to rubber byapplying RFL bonding agent which is generally employed for improving therubber adhesion of synthetic fibers.

A further object of the present invention is to improve the rubberadhesion properties of fibrous polyester materials by an easy andinexpensive method.

According to thepresent invention, it has now been found possible toimpart high rubber adhesion to fibrous polyester materials by a processcomprising the steps of applying to a fibrous polyester material asolution of an'amine compound having at least two primary or secondaryamino groups, heating the resulting fibrous material at a'temperatureabove 50C. and

below the melting point of the polyester, and then treating said fibrousmaterial with an organic solvent solution of aliphatic or aromaticpoly-carboxylic acid halide having at least two acid halide groups.

vcluding The polyesters employed in the present invention are highmolecular weight polyesters containing the carboxylic ester linkage asthe main recurring structural unit. These polyesters aregenerallyobtained from 0:,wglycols and dicarboxylic acids, and arepreferably high molecular weight aromatic polyesters which are ob--tained from polymethylene glycols and aromatic dicarboxylic acids, suchas' for example, polyethylene terephthalate, which is derived fromethylene glycol and ,terephthalic acid.

In the present invention, the fibrous materials include staples,filaments, yarns, threads, cords, woven fabrics, knitted fabrics,nonwoven fabrics and the like. These fibrous materials can containadditives or oiling agents such as catalysts, stabilizers, delusteringagents and pigments employed in the course of manufacture thereof.

In the first stage of the present invention, the amine compounds to beapplied to the polyester are compounds having at least two primary orsecondary amino groups and can be widely selected from amino compoundshaving either low molecular weights or high molecular weights. Forinstance, aliphatic amines inethylenediamine, hexamethylenediamine,triethylenetetramine, polyethylene imine and the like, and aromaticamines including metaphenylene diamine, methylene diamino phenyl methaneand the like. These amine compounds can be employed alone or incombination with other similar amine compounds. Among these aminecompounds, polyethylene imines having molecular weights of less than100,000 are preferably used in the invention.

In the present invention, the amine compounds are applied to the fibrouspolyester materials in the form of a solution. Solvents for this purposeare, preferably, water and lower alcohols such as methanol and ethanolfrom the viewpoint of cost, toxicity to human bodies and handling;however, ketones such as acetone and methyl ethyl ketone can also beused, if desired.The concentration of the amine compound in the solutioncan range from 0.01 to 50 weight percent, and preferably, ranges from0.1 to 10 weight percent. The solution of an amine compound can beapplied to the polyester material at temperatures ranging from roomtemperature to C. by dipping'the polyester material into said solution,by coating or spraying said solution onto said polyester material or bya combination thereof. The period of treatment is usually less thana fewminutes. It is also possible to conduct the first stage process togetherwith an oiling agent treatment by admixing the amine compound in theoiling bath.

in order to obtain enhanced adhesion of the polyester, material torubber in accordance with the present invention, at least about 0.01weight percent of the amine compound must be picked up and retained bythe polyester material during treatment with the amine solution. Sincedeposition of too much of the amine compound tends to impair the fibrousmaterials, a pick-up of less than 3 weight percent of the amine compoundby the polyester material is preferred. The amine compound deposited onthe fibrous polyester material reacts with an aliphatic or aromaticpolycarboxylic acid halide applied to the polyester material in thethird stage of the process of the present invention to produce hydrogenhalide by-product. Thus, if desired, a small amount of an alkalinesubstance such as caustic soda, caustic potash and/or alkali metal saltssuch as sodium bicarbonate acting as an acceptor for the hydrogen halidecan be added to the solution of the amine compound which is employed inthe first stage of the present invention.

The amine-treated fibrous polyester materials obtained in the firststage, are next subjected to a heat treatment in the second stage of thepresent invention. Although not wishing to. be bound by any theory ormechanism, it is currently believed that a portion of the amine compoundwhich has been applied to the polyester material will react with theester linkages of the polyester during the heat treatment and therebyproduce amide linkages. Thus, the second stage may give rise to chemicalcombination of the amine component with the polyester. In any event, theheat treatment in the second stage of the present invention isconsidered critical in order that the fibrous polyester materialstreated in accordance with the present invention may strongly adhere torubber by the application of RFL bonding agents.

The, heat treatment in the second stage is conducted at a temperature ofnot less than 50C. and below the melting point of polyesters, preferablyat 80-200C., and usually for a short time of less than a few minutes.Hot air, hot pins, hot plates, hot rollers and the like can be used forheating. The heat treatment also serves as a means for removing thesolvent from the solution of the amine compound which has been appliedto the fibrous polyester material in the first stage. This heattreatment can be conducted in combination with the drawing and heat-settreatment usually employed in the preparation of polyester fibers.

Typical of the aliphatic or aromatic polycarboxylic acid halides havingat least two acid halide groups which can be employed in the third stageof the present invention are, for example, (A) diacid halides of oxalicacid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelicacid, suberic acid azelaic acid, tricarballylic acid, 3-carboxy adipicacid, 4-carboxy pimelic acid, terephthalic acid, ortho phthalic acid,isophthalic acid, naphthalene-l,2-dicarboxylic acid, trimellitic acid,trimesic acid, benzene-l,2,3,4-tetracarboxylic acid andnaphthalene-1,S-dicarboxylic acid, (B) triacid halides of tricarballylicacid, 3-carboxy adipic acid, 4- carboxy pimelic acid, trimellitic acidand trimesic acid and (C) tetra-acid halides of benzene-l,2,3,4-tetracarboxylic acid. Diacid halides of saturated aliphaticdicarboxylic acids having two to carbon atoms and diacid halides ofbenzene dicarboxylic acids, for example, adipic acid dihalide andterephthalic acid dihalide are preferably used in the invention. Benzenedicarboxylic acid dihalides are most preferred since, as compared withaliphatic dicarboxylic acid dihalides, they are more stable uponexposure to moisture, less decomposable during storage and also easy tohandle. The halides employed are preferably the chlorides or bromides.

The polycarboxylic acid halides are dissolved in organic solvents foruse in the treatment of the fibrous polyester materials of the presentinvention. Typical solvents which can be employed are liquid aliphatichydrocarbons such as n-hexane and n-octane; halogenated. aliphatichydrocarbons such as dichloromethane, chloroform, carbon tetrachloride;

aromatic hydrocarbons such as benzene, toluene and xylene; halogenatedaromatic hydrocarbons such as monochlorobenzene and dichlorobenzene;ethers such as ethyl ether and butyl ether; ketones such as acetone andmethyl ethyl ketone; esters such as ethyl acetate, nbutyl acetate may beused.

The concentration of the polycarboxylic acid halide in the solution usedfor treating the polyester materials generally ranges from 0.1 to 30weight and preferably ranges from 0.5 to 10 weight percent.

In the third stage of the process of the present invention, the solutionof aliphatic or aromatic polycarboxyl ic acid halides having at leasttwo acid halide groups is applied to the polyester materials which havebeen subjected to heat treatment in the abovedescribed second stage, ina similar manner to that employed in treating,

the polyester material with amine compound solution in the first stage.The amine compounds already coated on the surface of the fibrouspolyester materials thereby react with the polycarboxylic acid halidesto produce linear or cross-linked polyamides. Accordingly, it isdesirable that a sufficient amount of polycarboxylic acid halide beemployed in the organic solvent to react with all of the amine compoundon the fibrous material. Since the reaction between the acid halides andamino groups is rapid even at a low temperature, the treatment of thepolyester materials with an organic solvent solution of polycarboxylicacid halide can be satisfactorily conducted at room temperature. Ifdesired, however, temperatures ranging from 0 to C. can be used for thetreatment, Contacting the polyester materials with treating agent in thethird stage need not be any longer than a few minutes, and preferably,the third stage contact time ranges from 0.1 to 60 seconds. The fibrouspolyester materials obtained from the above treatment can be washed witha dilute aqueous solution of caustic soda or caustic potash to eliminatehydrogen halides produced by the reaction which, if not removed, canform salts with the amino groups. Thereafter, the polyester material canbe further washed with water and dried.

The fibrous polyester materials obtained through treatment in accordancewith the present invention are covered with polyamides produced by thereaction of amine compounds and polycarboxylic acid halides, and saidpolyamides are at least partially chemically combined with the polyestermaterials probably because the amine compound chemically combines withthe polyester. Enhanced rubber adhesion can be achieved, even though theamount of the polyamide so produced is only a few percent or less of theweight of the polyester material. It is generally not considerednecessary to produce a polyamide coating of more than 10 percent of theweight of the polyester materialsto achieve enhanced rubber adhesion.

The amine compounds and aliphatic or aromatic polycarboxylic acidhalides used in the present invention are inexpensive, and are used insmall amounts. However, it has been found that treatment in accordancewith the present invention can impart excellent rubber adhesionproperties to the polyester materials. Accordingly, the presentinvention can be economically conducted without damaging variousdesirable properties which are inherent in the polyester materials.

The method of the present invention is advantageously applied to undrawnor drawn filaments. Undrawn filaments can be drawn and heat-set afterthe treatment. Further, the method of the present invention can also beapplied to fibrous materials other than filaments such as cords andwoven fabrics, and the same effects are attainable regardless of theforms of said materials. Since the treatment of polyester materials inaccordance with the present invention does not harden or stiffen saidmaterials, such an operation as twisting the treated fibers into cordscan be carried out in an entirely comparable manner as in the case ofuntreated fibers without any difficulties. Fibrous polyester materialstreated by the present invention exhibit a strong adhesion to rubberupon subsequent use of RFL bonding agents, and the obtained adhesiveforce is high not only at around room temperature but also attemperatures as highas 100C. Moreover, the degree of deterioration ofthe rubber adhesion imparted by the present invention is low even whenmaintained for a long time at a high temperature.

The present invention is further illustrated by the following examples.Unless otherwise specified, all percentages and parts are by weight.

EXAMPLE 1 A spun yarn of polyethylene terephthalate (600denier/200'filaments) was drawn six times and heat-set to obtain a fiberof 1000 denier/200 filaments.

This fiber was dipped into an aqueous solution containing 0.5 weightpercent polyethylene imine having a number-average molecular weight of1,200 and then subjected to drying and heat treatment for 1 minute at150C. after squeezing the liquid. The thus treated fiber was then dippedin a n-hexane solution of adipic acid dichloride (2 weight percent) for30 seconds, and then the solvent was removed by evaporation at 50C.

Two of the thus treated fibers were twisted to make a tire cord of 1,000d/l/2. The twist number was 470 turns/meter in a twist per yarn, and 470turns/meter in twist per ply yarn. The cord thus obtained was dipped ina RFL dispersion of the recipe shown in the table 1 below, andthereafter the product was subjected to drying and heat treatment forone minute at 190C.

TABLE 1 (1) Resorcinol 130 parts by weight Formalin (37%) 190 parts byweight Sodium hydroxide Water (2) Vinyl pyridine latex (40%) (registeredtrademark Hycar-2518FS" made by Japan Geon Co.,

Ltd.) (3) Water 1.3 parts by weight 1,200 parts by weight 3,000 parts byweight 1,500 parts by weight (1) was aged for six hours at roomtemperature after stirring. and further admixed with (2) and (3) andaged subsequently for 16 hours. The resultant product was used.

TA BLE 2 Rubber Compound A Natural rubber parts by weight Zinc Oxide 3parts by weight Carbon black 35 parts by weight Stearic acid 1.5 partsby weight I Fine tar 5 parts by weight Accelerator 1 parts by weightSulfur 3 parts by weight Antioxidant 1 parts by weight Rubber Compound BNatural rubber 50 parts by weight SBR 50 parts by weight Zinc Oxide 2.5parts by weight Carbon black 30 parts by weight Stearic acid 1 parts byweight Pine tar 5 parts by weight Accelerator 2.5 parts by weight Sulfur2 parts by weight Antioxidant 1 parts by weight An adhesion test wasconducted in accordance with the conventional H Piece test bydetermining the force required to pull out a cord being buried in therubber of 1 cm width (at a temperature of 20C.). The results are shownin the table 3. For comparative purposes, the

results of the case (comparative example 1) where treatment withpolyethylene imine was omitted and a treatment with adipic aciddichloride and the subsequent operations were carried out, the case(comparative example 2) where the treatment with adipic acid dichloridewas omitted; the case (comparative example 3) where only RFL treatmentand the subsequent operations were carried out and the case (comparativeexample 4) where the cord was treated with glycerol diglycidyl ether(epoxy compound) and hex- As is apparent from table 3, the presentinvention provides excellent rubber adhesion as compared with that ofthe other methods of treatment.

EXAMPLE 2 Example 1 was repeated using a n-hexane solution(concentration:- 2 weight percent of terephthalic acid dichloride inlieu of the n-hexane solution (concentration: 2 weight percent) ofadipic acid'dichloroide. The results are shown in table 4. Forcomparative purposes, the result of the case (comparative example 5)where treatment with polyethylene imine was omitted and treatment withterephthalic acid dichloride and the subsequent operation were carriedout is also shown.

TABLE 4 Adhesive force (k lcm) Rubber Rub er Compound A Compound BExample 2 in the same manner as that of example 1.

Comparative Example 5 7.9 8.1 solution heat heat- Compound Comd ofpolytreattreat- A li EXAMPLES 3-11 e h imine ment ment A polyethyleneterephthalate yarn 1,000 denier/200 5 f x (oc) (secmds) filaments) wasdipped in an aqueous solution of 01 eth lene imine of number-avera emolecular svei ght if 1,200 of various concentratior s as shown inexample i 1 Z3 S13 :32 table and was subjected to drying and heattreatment 14 200 30 13.4 13.2 at a temperature and for a period as'shownin table 5 :2 2g 21 {if after having been squeezed with rollers. Theyarn was 17 200 30 13.7 13.6 then treated with a n-hexane solution of 2weight per- 18 E 30 cent adipic acid dichloride. After being dried, theyarn 20 u 200 30 13.6 was twisted to make tire cord of 1,000 d/1/2. Thetwist number (470 turns/m) X (470 turns/m). The cord thus obtained wastreated with the RFL dispersion EXAMPLES 2149 described in table 1, andwas adhered to the rubber Employing a n-hexane solution (concentration:2 compounds described in table 2. The resultsof the adweight percent) oftrimellitic acid trichloride in lieu of I hesion test are shown in table5. Comparative example the n-hexane solution (concentration: 2 weightper- 6 showing the result of a rayon tire cord of 1,650 d/ /2 cent) ofadipic acid dichloride, examples 3-11 were rewhich has been treated withRFL is also shown in table peated, The results are shown in table 7. Inadhesion 5. The determination of adhesive force was conducted test, therubber compound A of table 2 was employed.

. TABLE 7 TABLE 5 Treating Conditions Treating Conditions Adhesive forceh p Adhesive force (kg/cm) tration concentra- Temper- Time Rubber Rubber0f the of (kg/Cm) tion of ature of of Com- Comq f h solution of heatheat he aqueous heat heat pound pound of P solution treattreat- A B f'hy of polyim ne ngent ment ethyllene ment C ment g 5660111115) imine(weight (seconds) example 21 0.1 150 30 13.0 example 3 0.1 150 30 13.213.0 22 60 1 -2 4 60 13,5 13,2 23 200 30 13.1 5 200 30 13.4 13.1 24 1 3013.9 6 0.5 150 30 14.6 14.3 25 60 13.6 7 60 14.3 13.9 26 200 30 13.4 8200 30 13.8 13.6 27 1.00 150 30 13.8 9 1.0 150 30 14.4 14.4 28 60 13.810 60 14.3 14.0 29 200 30 13.4 11 200 30 13.9 13.7 Comparative A Example6 13.0 12.9 EX MPLES 30 32 A polyethylene terephthalate fiber 1,000denier/200 filaments) was dipped in an aqueous solution As is apparentfrom table 5, the present invention im- (concentration of 0.5 percent)of polyethylene imine of parts adhesion'to the polyethyleneterephthalate fiber number-average molecular weight of 1,800 and driedcord which is as good as the rubber adhesion of the and heat treated for30 seconds at 150C. after having rayon tire cord. been squeezed withrollers. The so-treated fiber was In adhering rubber compound A to tirecord, the addipped in a n-hexane solution of adipic acid dichloridehesive force obtained in example 7 and comparative of the concentrationshown in table 8 for a period of 10 example 6 dropped, respectively to12.7 kg/cm and 7.6 seconds. kg/cm at 100C. After drying, the two yarnswere plied to make a tire cord of 1,000 d/l/2. The cord thus obtainedwas di ed EXAMPLES in the RFL dispersion of table 1, dried and heat trea ied E l i a hexane l i (concentration; 2 for a period ofl minute at190C. The treated cord was weight percent) of sebacic acid dichloride inlieu of the adhered to the l' compounds described in table n-hexanesolution (concentration: 2 weight percent) of The results of theadhesion test are Shown in table adipic acid dichloride, examples 3-11were repeated.

The results are shown in table 6. TABLE 8 Concentration of Adhesiveforce (kg/cm) TABLE 6 adipic acid Rubber A Rubber B dichloride Adhesiveforce (weight Treatin Conditions (kg/cm) 6 5 Concenempcr- Time trationexample 30 0.1 13.6 13.4

of the v ature of of Rubber Rubber 31 2.0 14.3 14.0

aqueous 32 13.3 13.2

EXAM PLES 33-35 Employing sebacic acid dichloride in lieu of adipic aciddichloride, examples 30-32 were repeated. The results are shown in table9.

TABLE 9 Concentration of Sebacic acid Adhesive force (kg/cm) Rubber ARubber B 10 EXAMPLES 36-38 Employing terephthalic acid 7 dichloride inlieu of adipic acid dichloride, examples 30-32 were repeated. Theresults are shown in table 10.

TABLE 10 Concentration of Adhesive Force (kg/cm) terephthalic acidRubber A Rubber B dichloride (weight example 36 0.1 13.7 13.5 37 2.014.1 13.9 38 10.0 13.4 13.3

EXAMPLES 39-42 A polyethylene terephthalate yarn 1 ,000 denier/200filaments) was dipped in an aqueous solution of polyethylene imine ofnumber average molecular weight of 1,200 containing sodium bicarbonateas an additive, and squeezed with rollers. After being dried and heattreated in an oven 'at '100C., the yarn was dipped into a carbontetrachloride solution of 2 weight percent adipic acid" dichloride for aperiod of 20 seconds. After being dried, the two yarns were plied to 40a twist number of (470 turns/m) X (470 turns/m) to give a tire cord of1,000 d/l/2. T-he thus obtained cord was treated with the RFL dispersiondescribed in'table 1, and was then adhered to rubber in the same manneras in example 1. The results are shown in table 1 1.

Analysis with an attenuated total reflection infrared spectrometerandthe weight increase showed that, in example 42, the fiber 'obtainedafter the treatment with adipic acid dichloride was deposited with 0.3percent of polyamide based on the weightof thefiber.

EXAMPLES '43-47 A polyethylene terep'hthalatetire cord (1,000 d/1/2,twist number (470 turns/m) X (470 turns/m) was dipped into-an aqueoussolution of polyethylene imine of number average molecular weight 1,800and then, after beingsqueezed of the excess solution by rollers, theresulting cord was heat treated under non-relaxed conditions.Subsequently, this tire cord was passed through a 2 weight percentn-hexane solution of adipic acid dichloride. The period for immersion inthe solution was 10 seconds. After drying, the tire cord was treatedwith RFL dispersion as described in example 1. Employing the rubbercompounds used in example 1, adhesion tests of the tire cords werecarried out. The results are shown in table 12. For comparativepurposes, the results of the case where treatment with adipic aciddichloride was omitted (Comparative examples 7, 8, 9, 10, 11) are alsoshown in table 12.

' TABLE 12 Concen- Heat Treatment Adhesive force tration of poly-(kg/cm) ethylene Temper- Time Rubber Rubber imine (weight ature(minutes) A B example 43 1.0 0.5 13.9 13.7 '44 0.5 0.5 14.0 14.1 45 0.51.0 14.2 14.0 46 1.0 0.5 14.3 13.9 47 5.0 0.5 14.0 13.9 Comparativeexample 7 0.1 0.5 8.3 8.1 8 0.5 0.5 9.3 9.4 9 1.0 0.5 9.8 9.6 10 1.0 1.010.2 9.9 11 5.0 0.5 9.9 9.5

EXAMPLES 48-52 Examples 43-47 were repeated usinga n-hexane solution ofterephthalic acid dichloride (concentration: 2 weight percent) in lieuof the n-hexane solution of adipic acid dichloride (concentration: 2weight percent). The results are shown in table 13. For comparativepurposes, the results of cases where heat treatment was eliminated (thetire cord was dried at room temperature) are shown as comparativeexamples, 12 to 14.

EXAMPLES53-57 Employing a nhexane solution (concentration: 2 weightpercent) of trimesic acid trichloride in lieu of the n-hexane solution(concentration: 2 weight percent) of adipic acid dichloride, examples43-47 were repeated. The results are shown in table 14. In the adhesiontests, rubber compound A was employed.

TABLE 14 EXAMPLES 58-60 A polyethylene terephthalate fiber (1,000denier/200 filaments) was dipped into a 1 weight percent aqueoussolution of a variety of amine compounds as shown in table 15. Afterexcess solution was squeezed out of the fiber with rollers, the fiberwas subjected to drying and heat treatment for three minutes at 70C. Thefiber was then dipped into a n-hexane solution of 2 weight percentadipic acid dichloride for a period of seconds. After being dried, thesefilaments were plied to produce a tire cord of 1,000 d/1/2, having thetwist number of (470 turns/m) X (470 turns/m). This cord was treatedwith the RFL dispersion of table 1. Table 15 summarizes the excellentresults obtained in the adhesion test with the rubber compounds of table2.

TABLE 15 EXAMPLES 6l63 A polyethylene terephthalate fiber of the typeused in examples 58-60 was dipped into an aqueous solution(concentration: 0.5 percent) of polyethylene imine having anumber-average molecular weight of 1,200, and subjected to drying andheat treatment for the period of 1 minute at 150C. after the excesssolution had been squeezed out of the fiber. This fiber wa sthen dippedinto a n-hexane solution of adipic acid dibromide having a variety ofconcentrations as shown in table 16 for seconds. The fiber was thenwashed with water and dried, and plied to give a tire cord of 1,000d/l/2 having a twist number (470 turns/m) X (470 turns/m). The tire cordwas treated with the RFL dispersion of table 1. Table 16 shows theexcellent results obtained in the adhesion tests carried out with therubber compounds of table 2.

acid dibromide (weight Rubber A Rubber 8 example 61 EXAMPLES 64-66Employing pimelic acid dichloride in-lieu of adipic acid dibromide,examples 61-63 were repeated. The

results are shown in table 17.

TABLE 17 Concentration of pimelic Adhesive force g/ acid dichloride(weight Rubber A Rubber B example 64 0.5 13.7 65 1.0 14 1 13.9 66 2.014.0'

EXAMPLES 67-72 Employing a n-hexane solution (concentration: 1 weightpercent of the various aliphatic dicarboxylic acid dihalides enumeratedin table 18 in lieu of the nhexane solution of adipic acid dibromide,example 62 was repeated. The results are shown in table 18. The rubbercompound A of table 2 was used in the adhesion test.

TABLE 18 Acid Halide Adhesive force (kg/cm) example 67 Oxalic aciddichloride 13.8 68 Malonic acid dichloride 13.7

69 Succinic acid dichloride 13.5

70 Glutanc acid dichloride 13.5

71 Azelaic acid dichloride 13.4

72 Sebacic acid dibromide 13.3

EXAMPLES 7375 Employing terephthalic acid dibromide in lieu of adipicacid dibromide, examples 61-63 were repeated. The results are shown intable 19.

TABLE 19 Adhesive force g/c Concentration of dichlorides summarized inthe following table 20 in lieu of adipic acid dibromide, example 62 wasrepeated. The results are shown in table 20. The rubber compound A oftable 2 was used in the adhesion test.

TABLE 20 Aromatic dicarboxylic Adhesive force (kg/cm) acid dichlorideexample 76 Orthophthalic acid 13.6

dichloride 77 lsophthalic acid 13.4

dichloride 78 Naphthalene dicarboxylic 13.3

acid dichloridc EXAM PLES 79-81 Examples 61-63 were repeated usingbenzenel,2,3,4-tetracarboxylic tetrachloride in lieu of adipic aciddibromide. The results are shown in table 21. The rubber compound A oftable 2 was used in the adhesion test.

TABLE 21 Concentration of benzene- Adhesive force 1,2,3,4-tetracarboxylic (kg/cm) tetrachloride (weight example 79 0.5 13.080 1.2 13.7 81 2.0 13.8

EXAMPLES 82-85 Employing the various carboxylic acid trihalidesenumerated in the following table 22 in lieu of adipic acid 'dibromide,example 62 was repeated. The results are shown in table 22.

' The rubbercompound A of the table 2 was used in the adhesion test.

TABLE 22 Acid Halide Adhesive force (kg/cm) example 82 tricarballylicacid 13.4

trichloride 83 3-carboxy adipic acid 13.1

trichloride 84 4-carboxy pimelic acid 13.1

trichloride 85 trimellitic acid 13.2

tribromide EXAMPLES 86-89 Polyethylene terephthalate tire cords of thetype used in examples 43-47 were dipped into methanol solutions(concentration: 1.0 weight percent) of polyethylene imine or ethylenediamine and heat treated under the conditions shown in table 23 afterhaving the excess solutionsqueezed out.

The heat treated cords were dipped into a n-hexane solution(concentration: 2 weight percent) of adipic acid dichloride fora periodof 10 seconds, dried and treated with the RFLdispersion of table 1, andthen adhered to the rubber compound A in the identical manner as inexample 1. The results are shown in table 23.

What is claimed is:

1. Process for the treatment of polyesters impart enhanced rubberadhesion thereto which comprises ap: plying to a polyester, a solutionof an amine compound having at least two primary or secondary aminogroups, subjecting the resulting polyester to heat treatment at atemperature above 50C. and below'the melting point of the polyester,then treating the heat treated polyester with a solution of an aliphaticor aromatic polycarboxylic acid halide having at least two acid halidegroups in an organic solvent, and evaporating the solvent, wherebyenhanced rubber adhesion is imparted thereto.

2. Process as defined in claim 1 wherein the polyester is an aromaticpolyester.

3. Process as defined in claim l wherein the amine compound is apolyethylene imine having a molecular weight of less than 100,000.

4. Process as defined in claim 1 wherein the solution of the aminecompound is an aqueous solution.

5. Process as defined in claim 1 wherein the solution of the aminecompound is a lower alcoholic solution.

6. Process asdefined in claim 1 wherein the concentration of the aminein the solution ranges from 0.01 to 50 weight percent.

7. Process as defined in claim 1 wherein the solution of amine compoundis applied to the polyester at temperatures ranging from roomtemperature to 100C.

8. Process as defined in claim 1 wherein from 0.01 to 3 weight-percentof the amine compound is picked up by the polyester during treatment.

9. Process as defined in claim 1 wherein the solution of amine compoundadditionally contains an alkaline hydrogen halide acceptor.

10. Process as defined in claim 1 wherein the heat treatment isconducted at temperatures of from 80 to 200C.

11. Process as defined in claim 1 wherein the amine compound is apolyethylene imine, and the aliphatic or aromatic polycarboxylic acidhaving at least two acid halide groups is a saturated aliphaticdicarboxylic acid halide containing from two to 15 carbonatoms or abenzene dicarboxylic acid dihalide.

12. Process as defined in claim 1 wherein the concentration of thealiphatic or aromatic polycarboxylic acid halide in the treatingsolution ranges from 0.1 to 30 weight percent.

13. Process as defined in claim 1 wherein the aliphatic or aromaticpolycarboxylic acid halide solution is applied to the polyester attemperatures ranging from 0? to 100C lWProcess as defined in claim 1wherein the aliphatic or aromatic polycarboxylic acid halide solution isapplied to the polyester for a period of time ranging from 0.1 to 60seconds.

15. Process as defined in claim 1 wherein the resulting polyester iswashed with an aqueous alkaline solution to remove hydrogen halidesproduced during treatment.

16. Process as defined in claim 1 wherein an aqueous dispersion of amixture of a partially condensed resorcinol-formaldehyde resin in avinyl pyridine copolymer latex is applied to the treated polyester toeffect adhesion to rubber.

17. A fibrous polyester material exhibiting enhanced adhesion to rubberprepared by the process of claim weight percent of a saturated aliphaticdicarboxylic acid dihalide containing from two to carbon atoms inorganic solvent, and evaporating the solvent.

20. Process for treating fibrous polyester materials which comprisesapplying to a fibrous polyethylene terephthalate material, an aqueous oralcoholic solution of a polyethylene imine having a concentration of 0.1to 10 weight percent, heating the resulting material at a temperature offrom 80 to 200C., then applying to the heat treated material a 0.5 to 10weight percent solution of a benzene dicarboxylic acid dihalide in anorganic solvent, and evaporating the solvent.

1. Process for the treatment of polyesters impart enhanced rubberadhesion thereto which comprises applying to a polyester, a solution ofan amine compound having at least two primary or secondary amino groups,subjecting the resulting polyester to heat treatment at a temperatureabove 50*C. and below the melting point of the polyester, then treatingthe heat treated polyester with a solution of an aliphatic or aromaticpolycarboxylic acid halide having at least two acid halide groups in anorganic solvent, and evaporating the solvent, whereby enhanced rubberadhesion is imparted thereto.
 2. Process as defined in claim 1 whereinthe polyester is an aromatic polyester.
 3. Process as defined in claim 1wherein the amine compound is a polyethylene imine having a molecularweight of less than 100,
 000. 4. Process as defined in claim 1 whereinthe solution of the amine compound is an aqueous solution.
 5. Process asdefined in claim 1 wherein the solution of the amine compound is a loweralcoholic solution.
 6. Process as defined in claim 1 wherein theconcentration of the amine in the solution ranges from 0.01 to 50 weightpercent.
 7. Process as defined in claim 1 wherein the solution of aminecompound is applied to the polyester at temperatures ranging from roomtemperature to 100* C.
 8. Process as defined in claim 1 wherein from0.01 to 3 weight percent of the amine compound is picked up by thepolyester during treatment.
 9. Process as defined in claim 1 wherein thesolution of amine compound additionally contains an alkaline hydrogenhalide acceptor.
 10. Process as defined in claim 1 wherein the heattreatment is conducted at temperatures of from 80* to 200*C.
 11. Processas defined in claim 1 wherein the amine compound is a polyethyleneimine, and the aliphatic or aromatic polycarboxylic acid having at leasttwo acid halide groups is a saturated aliphatic dicarboxylic acid halidecontaining from two to 15 carbon atoms or a benzene dicarboxylic aciddihalide.
 12. Process as defined in claim 1 wherein the concentration ofthe aliphatic or aromatic polycarboxylic acid halide in the treatingsolution ranges from 0.1 to 30 weight percent.
 13. Process as defined inclaim 1 wherein the aliphatic or aromatic polycarboxylic acid halidesolution is applied to the polyester at temperatures ranging from 0* to100*C.
 14. Process as defined in claim 1 wherein the aliphatic oraromatic polycarboxylic acid halide solution is applied to the polyesterfor a period of time ranging from 0.1 to 60 seconds.
 15. Process asdefined in claim 1 wherein the resulting polyester is washed with anaqueous alkaline solution to remove hydrogen halides produced duringtreatment.
 16. Process as defined in claim 1 wherein an aqueousdispersion of a mixture of a partially condensed resorcinol-formaldehyderesin in a vinyl pyridine copolymer latex is applied to the treatedpolyester to effect adhesion to rubber.
 17. A fibrous polyester materialexhibiting enhanced adhesion to rubber prepared by the process of claim16.
 18. A polyester exhibiting enhanced adhesion to rubber prepared bythe process of claim
 1. 19. Process for treating fibrous polyestermaterials comprising applying to a fibrous polyethylene terephthalatematerial, an aqueous or alcoholic solution Of a polyethylene imine in aconcentration of from 0.1 to 10 weight percent, heating the resultingmaterial at a temperature of from 80* to 200*C., then applying to theheat treated material a solution comprising 0.5 to 10 weight percent ofa saturated aliphatic dicarboxylic acid dihalide containing from two to15 carbon atoms in organic solvent, and evaporating the solvent.